U.S. patent number 4,370,224 [Application Number 06/317,116] was granted by the patent office on 1983-01-25 for reforming with multimetallic catalysts.
This patent grant is currently assigned to Exxon Research and Engineering Co.. Invention is credited to William C. Baird, Jr., Paul E. Eberly, Jr., Charles H. Mauldin.
United States Patent |
4,370,224 |
Eberly, Jr. , et
al. |
* January 25, 1983 |
Reforming with multimetallic catalysts
Abstract
A catalyst comprised of platinum, iridium, copper, selenium and
halogen, composited with an inorganic oxide support or carrier,
preferably alumina. The catalyst is one which possesses an
intrinsically high activity, is stable, and can operate at
reforming conditions at high severities.
Inventors: |
Eberly, Jr.; Paul E. (Baton
Rouge, LA), Mauldin; Charles H. (Baton Rouge, LA), Baird,
Jr.; William C. (Baton Rouge, LA) |
Assignee: |
Exxon Research and Engineering
Co. (Florham Park, NJ)
|
[*] Notice: |
The portion of the term of this patent
subsequent to May 5, 1998 has been disclaimed. |
Family
ID: |
26731785 |
Appl.
No.: |
06/317,116 |
Filed: |
November 2, 1981 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
211765 |
Dec 1, 1980 |
|
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53375 |
Jun 29, 1979 |
4265786 |
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Current U.S.
Class: |
208/139 |
Current CPC
Class: |
B01J
23/8926 (20130101); C10G 35/09 (20130101); B01J
27/0573 (20130101) |
Current International
Class: |
B01J
23/89 (20060101); B01J 27/057 (20060101); C10G
35/09 (20060101); C10G 35/00 (20060101); C10G
035/085 () |
Field of
Search: |
;208/139 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Davis; Curtis R.
Attorney, Agent or Firm: Proctor; Llewellyn A.
Parent Case Text
RELATED APPLICATIONS
This is a division of application Ser. No. 211,765, filed Dec. 1,
1980, which is a continuation-in-part of application Ser. No.
053,375; filed June 29, 1979, now U.S. Pat. No. 4,265,786.
Claims
Having described the invention, what is claimed is:
1. A process for reforming a hydrocarbon feed at reforming
conditions which comprises contacting said feed with a catalyst
which comprises from about 0.1 to about 2 percent platinum, from
about 0.1 to about 2 percent iridium, from about 0.01 to about 0.1
percent copper, from about 0.001 to about 3 percent selenium, and
from about 0.1 to about 2.5 percent halogen, composited with an
inorganic oxide support.
2. The process of claim 1 wherein the catalyst contains from about
0.2 to about 0.6 percent platinum.
3. The process of claim 1 wherein the catalyst contains from about
0.2 to about 0.6 percent iridium.
4. The process of claim 1 wherein catalyst contains from about
0.025 to about 0.08 percent copper.
5. The process of claim 1 wherein the catalyst contains from about
0.01 to about 1 percent selenium.
6. The process of claim 1 wherein the catalyst contains from about
0.2 to about 0.6 percent platinum, from about 0.2 to about 0.6
percent iridium, from about 0.025 to about 0.08 percent copper,
from about 0.01 to about 1 percent selenium, and wherein the copper
is composited with the catalyst in amount sufficient to provide an
atom ratio of copper:platinum ranging from about 0.008:1 to about
1.54:1.
7. The process of claim 6 wherein the catalyst contains from about
0.7 to about 1.2 percent halogen.
8. The process of claim 1 wherein the catalyst is sulfided, and
contains to about 0.2 percent sulfur.
9. The process of claim 8 wherein the catalyst contains from about
0.05 to about 0.1 percent sulfur.
Description
BACKGROUND OF THE INVENTION AND PRIOR ART
Catalytic reforming, or hydroforming, is a process well known to
the petroleum refining industry for improving the octane quality of
naphthas and straight run gasolines. In a typical process, a series
of reactors are provided with fixed beds of catalyst which receive
upflow or downflow feed, and each reactor is provided with a
preheater because the reactions which take place are endothermic. A
naphtha feed, with hydrogen, or recycle gas, is cocurrently passed
sequentially through a reheat furnace and then to the first
reactor, and then again preheated and passed to the next reactor of
the series. The vapor effluent from the last reactor of the series
is a gas rich in hydrogen, which usually contains small amounts of
normally gaseous hydrocarbons, from which hydrogen is separated
from the C.sub.5.sup.+ liquid product and recycled to the process
to minimize coke production; coke invariably forming and depositing
on the catalyst during the reaction.
Reforming catalysts are recognized as dual functional, the catalyst
composite including a metal, or metals, or a compound or compounds
thereof, providing a hydrogenation-dehydrogenatin (hydrogen
transfer) function and an acidic component providing an
isomerization function. The platinum group metals (ruthenium,
osmium, rhodium, iridium, palladium and platinum), particularly
platinum, have been widely used in commercial reforming operations,
these metals being composited with an inorganic oxide base,
particularly alumina; and in recent years promoters such as
iridium, rhenium, germanium, tin, etc., have been added,
particularly to platinum, to enhance one or more of certain of the
characteristics which a good reforming catalyst must possess-viz.,
activity, selectivity, activity maintenance and yield stability.
Halogen, e.g. chlorine, is generally added to provide the required
acid function.
The principal reactions produced in reforming are dehydrogenation
of naphthenes to produce the corresponding aromatic hydrocarbons;
isomerization of n-paraffins to form branched-chain paraffins and
isomerization of five membered to six membered ring compounds, and
dehydrogenation of the latter to form aromatics; dehydrocyclization
of paraffins to form aromatics; and hydrocracking of high molecular
weight feed constituents to form lower molecular weight, or lower
boiling, constituents, the net effect of these reactions being to
increase the concentration of aromatics and isomers, with
consequent octane improvement of naphthas boiling within the
gasoline range. Hydrogenolysis, a specific and severe form of
hydrocracking, can also occur. This reaction, inter alia, produces
excessive amounts of methane and other hydrocarbon gases with
decreased C.sub.5.sup.+ liquid yields which can be particularly
acute with multi-metallic catalysts.
U.S. Pat. No. 2,851,399 which issued Sept. 9, 1958, to Brennan et
al, discloses a reforming catalyst containing platinum and selenium
composited with alumina. In U.S. Pat. No. 3,884,799 to Mahoney et
al, which issued May 20, 1975, there is also disclosed a catalyst
and process for using such catalyst for reforming a petroleum
hydrocarbon fraction at conventional reforming conditions, which is
constituted of a Group VIII noble metal, notably platinum, and
rhenium and selenium composited on a refractory inorganic oxide,
notably alumina, to which is added a halogen component, notably a
chloride. This reference discusses the problem of hydrogenolysis
which occurs in reforming during start-up with an unsulfided, or
improperly sulfided, halogenated platinum-rhenium catalyst; and it
discloses and claims the process of using a reforming catalyst in
which selenium is incorporated therein thereby reducing coke
formation and eliminating any necessity of a pre-sulfiding
treatment of that particular catalyst to suppress hydrogenolysis
during start-up.
In U.S. Pat. No. 4,151,115 which issued Apr. 24, 1979, to Paul E.
Eberly, Jr., there is disclosed a reforming catalyst comprised of
alumina and a Group VIII noble metal hydrogenation-dehydrogenation
component, notably platinum, to which both iridium and selenium
have been added to promote the activity and selectivity of the
catalyst. The catalyst is prepared by a method wherein the selenium
is introduced into and deposited throughout the support, and
suitably the reforming catalyst contains a halogen component,
particularly chlorine; and preferably the selenium component is
introduced into the support, or catalyst, by impregnating same with
a solution comprising selenium as an element, or a salt or compound
thereof.
In copending application Ser. Nos. 029,675 and 034,596, filed Apr.
13, 1979 and Apr. 30, 1979, respectively, and now U.S. Pat. No.
4,251,391 and U.S. Pat. No. 4,251,392, respectively, there are also
disclosed catalysts and methods for the preparation of catalyst
compositions comprised of platinum or platinum and palladium,
rhenium, halogen, and preferably sulfur, composited with an
inorganic oxide support, or carrier, to which a small concentration
of copper is added to improve the yield and stability of the
catalyst in reforming. And, in Ser. No. 053,375, supra, there is
disclosed platinum-selenium catalysts to which a small amount of
copper has been added. Copper is an essential component of such
compositions; it having been found, inter alia, that excessive
C.sub.2.sup.+ hydrocarbon gas formation could be suppressed by the
use of small and critical concentrations of copper, and that added
benefits could be obtained by the further addition of sulfur to the
catalyst to suppress hydrogenolysis.
It is nonetheless an objective of the present invention to provide
a new and improved catalyst, and process for utilizing such
catalyst to upgrade naphthas by reforming to produce higher octane
gasolines.
A particular object is to provide a highly active catalyst, and
process for effecting, at suitable reforming conditions, the
production of high octane gasolines while minimizing hydrogenolysis
and other types of hydrocracking which tend to produce methane and
hydrocarbon gases of higher molecular weight than methane.
Another object is to provide a catalyst which is capable of
reforming feed of high sulfur level; the catalyst being
particularly resistant to sulfur poisoning.
These and other objects are achieved in accordance with the present
invention embodying a catalyst comprised of platinum, iridium,
copper, selenium, and halogen composited with an inorganic oxide
support, or carrier, preferably alumina. The catalyst possesses an
intrinsically high activity, and provides good yield and stability
in reforming. The catalyst may also contain a sulfur component.
The catalyst is one which contains platinum as an essential
component, generally in concentration ranging from about 0.1
percent to about 2 percent, preferably from about 0.2 percent to
about 0.6 percent, based on the weight of the catalyst (dry
basis).
The catalyst also contains iridium as an essential component,
generally in concentration ranging from about 0.1 percent to about
2 percent, preferably from about 0.2 to about 0.6 percent, based on
the weight of the catalyst (dry basis).
The catalyst also contains copper as an essential component,
generally in concentration ranging from about 0.01 percent to about
0.1 percent, preferably from about 0.025 percent to about 0.08
percent, based on the weight of the catalyst (dry basis).
Preferably, the copper is composited with the catalyst in amount
sufficient to provide an atom ratio of copper:(platinum plus
iridium) ranging from about 0.008:1 to about 1.54:1, preferably
from about 0.12:1 to about 0.61:1. The copper component is
conveniently added to the catalyst by impregnation. It is important
that the concentration of copper on the catalyst be controlled to
the proper level because high concentrations of copper act as a
poison and depresses catalyst activity.
Selenium is contained within the catalyst as an essential
component, suitably in concentration ranging from about 0.001 to
about 3 percent, preferably from about 0.01 to about 1 percent,
based on the weight of the catalyst (dry basis). The selenium is
incorporated into the catalyst at the time of its formation,
preferably by impregnation of a solution of a soluble salt, acid or
compound of selenium into the carrier. The selenium incorporation
step can be carried out simultaneously with, prior to, or following
the impregnation of the hydrogenation-dehydrogenation component, or
other components, into the carrier. Selenium, in accordance with
this invention, can be added to the carrier from a solution which
contains both the salt, acid, or compound of selenium, the
hydrogenation-dehydrogenation component, or other components, and
the inorganic acid such as HCl. Suitably, the salts or compounds
are dissolved in a suitable solvent, preferably water, to form a
solution, or each moiety is separately dissolved in a solution, the
solutions admixed and the admixed solution used for impregnation of
the carrier. The concentration of the salt or compound of selenium
in the impregnation solution ranges from about 0.01 to 2 percent,
preferably from about 0.01 to 1 weight percent, based on the weight
of the solvent; this concentration being adequate to impregnate a
sufficient amount of the selenium within the catalyst.
Halogen is an essential component, the halogen content of the
catalyst generally ranging from about 0.1 to about 2.5 percent,
preferably from about 0.7 to about 1.2 percent, based on the weight
of the catalyst (dry basis).
Sulfur is a preferred, but not an essential component. The sulfur
content of the catalyst generally ranges to about 0.2 percent,
preferably from about 0.01 percent to about 0.1 percent, based on
the weight of the catalyst (dry basis). The sulfur can be added to
the catalyst by conventional methods, suitably by breakthrough
sulfiding of a bed of the catalyst with a sulfur-containing gaseous
stream, e.g., hydrogen sulfide in hydrogen, performed at
temperatures of from about 350.degree. F. to about 1050.degree. F.,
and at pressures of from about 1 to about 40 atmospheres for the
time necessary to achieve sulfur breakthrough, or the desired
sulfur level.
The several components of the catalyst are composited with a
refractory inorganic oxide support material, particularly alumina.
Suitably, the copper is added first to the support, and
subsequently the other components are added. The halogen component,
particularly chlorine, is added along with the various components,
or subsequent thereto, or both. The support can contain, for
example, one or more of alumina, bentonite, clay, diatomaceous
earth, zeolite, silica, activated carbon, magnesia, zirconia,
thoria, and the like; though the most preferred support is alumina
to which, if desired, can be added a suitable amount of other
refractory carrier materials such as silica, zirconia, magnesia,
titania, etc., usually in a range of about 1 to 20 percent, based
on the weight of the support. A preferred support for the practice
of the present invention is one having a surface area of more than
50 m.sup.2 /g, preferably from about 100 to about 300 m.sup.2 /g, a
bulk density of about 0.3 to 1.0 g/ml, preferably about 0.4 to 0.8
g/ml, an average pore volume of about 0.2 to 1.1 ml/g, preferably
about 0.3 to 0.8 ml/g, and an average pore diameter of about 30 to
300 A.
The metal components can be composited or intimately associated
with the porous inorganic oxide support or carrier by various
techniques known to the art such as ion-exchange, coprecipitation
with the alumina in the sol or gel form, and the like. For example,
the catalyst composite can be formed by adding together suitable
reagents such as a salt of the required metals and ammonium
hydroxide or ammonium carbonate, and a salt of aluminum such as
aluminum chloride or aluminum sulfate to form aluminum hydroxide.
The aluminum hydroxide containing the salts can then be heated,
dried, formed into pellets or extruded, and then calcined in air or
other atmosphere. The metal hydrogenation-dehydrogenation
components are preferably added to the catalyst by impregnation,
typically via an "incipient wetness" technique which requires a
minimum of solution so that the total solution is absorbed,
initially or after some evaporation.
Suitably, the copper, and other metal components, is deposited on a
previously pilled, pelleted, beaded, extruded, or sieved
particulate support material by the impregnation method. Pursuant
to the impregnation method, porous refractory inorganic oxides in
dry or solvated state are contacted, either alone or admixed, or
otherwise incorporated with a metal or metals-containing solution,
or solutions, and thereby impregnated by either the "incipient
wetness" technique, or a technique embodying absorption from a
dilute or concentrated solution, or solutions, with subsequent
filtration or evaporation to effect total uptake of the metallic
components.
In compositing the metals with the carrier, essentially any soluble
compound of the respective metal can be used, but a soluble
compound which can be easily subjected to thermal decomposition and
reduction is preferred; for example, inorganic salts such as
halides, nitrates, inorganic complex compounds, or organic salts
such as the complex salt of acetylacetone, amine salt, and the
like. In adding the copper, copper chlorides and nitrates are
preferred sources of copper on the basis of availability, cost and
effectiveness.
The copper is incorporated into the catalyst at the time of its
formation, or thereafter, and preferably the copper is incorporated
into the pre-formed carrier by impregnation from a solution of a
soluble salt, or compound of copper; preferably in a solution of
hydrochloric acid to provide good distribution of the copper. This
step is carried out prior to the impregnation of the
hydrogenation-dehydrogenation components. The copper, in accordance
with this invention, can be added to the carrier from a solution
which contains a salt, or compound of copper, and thereafter the
copper impregnated support can be dried, calcined, and the
hydrogenation-dehydrogenation components then added, suitably as
salts or compounds dissolved in a suitable solvent, preferably
water, to form a solution.
The impregnation of the platinum component, and other components,
into a carrier is carried out by impregnating the carrier with a
solution, or solutions, of the respective salts or compounds of the
elements or metals to be incorporated. Salts, acids or compounds of
each metal can be dissolved in a solution, or the salts, acids or
compounds can be separately dissolved in solutions, the solutions
admixed, and the solution used for impregnation of the carrier. In
other words, copper is added initially using conventional
techniques, and then the other metals are added simultaneously or
sequentially, suitably by impregnation. The amount of impregnation
solution used should be sufficient to completely immerse the
carrier, usually within the range from about 1 to 20 times of the
carrier by volume, depending on the metal concentration in the
impregnation solution. The impregnation treatment can be carried
out under a wide range of conditions including ambient or elevated
temperatures and atmospheric or supratmospheric pressures.
In a preferred embodiment of the present invention a carrier is
impregnated with an aqueous halogen-acid solution of the copper.
Exposure to a halogen acid can introduce substantially high levels
of halogen into the carrier which is not desirable because
subsequent metal impregnation is inhibited and the catalyst can
produce high acid cracking in reforming. However, excess halogen
can be readily removed from the acid treated carrier by
neutralization with ammonium hydroxide, suitably by contact at
ambient temperature for periods ranging from about 0.1 to about 1
hour, at strengths ranging from about 0.1 N to about 15 N,
preferably from about 0.1 N to about 5 N. These treatments are
followed by evaporation or filtration and then drying or
calcination, or both, and then the metals impregnated catalyst can
be further impregnated with a solution containing (1) a dissolved
salt or compound of platinum, or platinum and additional metals,
(2) a dissolved salt or compound of iridium, (3) a dissolved salt
or compound of selenium, and (4) hydrochloric acid, followed by
evaporation or filtration, with subsequent drying or calcination,
or both, whereby the components are dispersed substantially
uniformly to the inner part of the catalyst.
As suggested, a halogen component is also required. Fluorine and
chlorine are preferred halogen components. The halogen is contained
on the catalyst in concentration ranging from about 0.1 percent up
to about 2.5 percent, preferably within the range of about 0.7 to
about 1.2 percent, based on the weight of the catalyst. The
introduction of halogen into catalyst can be carried out by any
method and at any time of the catalyst preparation; for example,
prior to, following or simultaneously with the impregnation of the
platinum, iridium, copper and selenium components. In the usual
operation, the halogen component is introduced simultaneously with
the incorporation of these metal components. It can also be
introduced by contacting a carrier material in a vapor phase or
liquid phase with a halogen compound such as hydrogen fluoride,
hydrogen chloride, ammonium chloride, or the like.
The catalyst, after impregnation, is dried by heating at a
temperature above about 80.degree. F., preferably between about
150.degree. F. and 300.degree. F., in the presence of nitrogen or
oxygen, or both, in an air stream or under vacuum. The catalyst is
calcined at a temperature between about 500.degree. F., preferably
about 500.degree. F. to 850.degree. F., in the presence of oxygen
in an air stream or in the presence of an inert gas such as N.sub.2
or in the presence of a mixture of O.sub.2 and inert gas. This
calcination or activation is conducted for periods ranging from
about 1 to about 24 hours in either flowing or static gases.
Reduction is performed by contact with flowing hydrogen at
temperatures ranging from about 350.degree. F. to about
1050.degree. F. for periods ranging from about 0.5 to about 24
hours at about 1-40 atm. The catalyst can be sulfided by use of a
blend of H.sub.2 S/H.sub.2 and performed at a temperature ranging
from about 350.degree. F. to about 1050.degree. F. at about 1-40
atm. for a time necessary to achieve breakthrough, or the desired
sulfur level. Post-sulfiding stripping can be employed if desired
at conditions similar to those for reduction of the catalyst.
Treatment of the catalyst with a mixture of chlorine and oxygen can
be substituted for air activation if desired. This procedure can
correct for any possible maldistribution of the metals arising from
improper impregnation, and the procedure is useful in restoring
activity during regeneration-rejuvenation after on oil service. A
blend of chlorine, oxygen, and nitrogen can also be employed at
temperatures ranging from about 350.degree. F. to about
1050.degree. F. for periods ranging from about 1 to about 24 hours
at 1-40 atm. Treat times for these various operations are a
function of gas flow rates, gas compositions, and conditions. The
catalyst halide content can be controlled during impregnation, or
adjusted by treatment with water or water-hydrogen chloride
blends.
This catalyst can be used in semi-regenerative, cyclic, semicyclic,
or continuous bed reforming. It is particularly useful in cyclic
reforming operations. The catalyst is particularly useful at severe
reforming conditions, especially at low pressures, or pressures
ranging from about 50 psig to about 150 psig, where maximum yield
is favored.
The feed or charge stock can be a virgin naphtha, cracked naphtha,
a Fischer-Tropsch naphtha, or the like. Typical feeds are those
hydrocarbons containing from about 5 to 12 carbon atoms, or more
preferably from about 6 to about 9 carbon atoms. Naphthas, or
petroleum fractions boiling within the range of from about
80.degree. F. to about 450.degree. F., and preferably from about
125.degree. F. to about 375.degree. F., contain hydrocarbons of
carbon numbers within these ranges. Typical fractions thus usually
contain from about 20 to about 80 vol. % paraffins, both normal and
branched, which fall in the range of about C.sub.5 to C.sub.12,
from about 10 to 80 vol. % of naphthenes falling within the range
of from about C.sub.6 to C.sub.12, and from 5 through 20 vol. % of
the desirable aromatics falling within the range of from about
C.sub.6 to C.sub.12.
The reforming runs are initiated by adjusting the hydrogen and feed
rates, and the temperature and pressure to operating conditions.
The run is continued at optimum reforming conditions by adjustment
of the major process variables, within the ranges described
below:
______________________________________ Major Operating Typical
Process Preferred Process Variables Conditions Conditions
______________________________________ Pressure, Psig 50-750
100-300 Reactor Temperature, .degree.F. 750-1100 850-1000 Gas Rate,
SCF/B 1500-10,000 2000-7000 (Incl. Recycle Gas) Feed Rate, W/Hr/W
0.5-10 1-3 ______________________________________
The invention will be more fully understood by reference to the
following demonstrations and examples which present comparative
data illustrating its more salient features. All parts are given in
terms of weight except as otherwise specified.
EXAMPLES
A series of catalysts (Catalyst A through E) were prepared from
portions of 1/16" high purity gamma alumina extrudates by calcining
same in air at 1000.degree. F. for 4 hours. Where copper was added,
the extrudates were impregnated overnight with a stock solution of
cuprous chloride in 1 N hydrochloric acid. The extrudates were
washed with water and soaked in ammonium hydroxide solution for 1
hour to remove excess chloride. After washing with water the
extrudates were impregnated with an aqueous solution of
chloroplatinic acid, perrhenic acid, or selenous acid, or admixture
thereof, as required, and hydrochloric acid using CO.sub.2 as an
impregnation aid. The catalysts were air-dried and then dried in
vacuum at 130.degree. F. overnight. The catalysts were air
activated and reduced. The composition of the catalysts are given
in Table I.
TABLE I ______________________________________ Catalysts Components
A B C D E ______________________________________ Platinum 0.3 0.3
0.3 0.3 0.3 Iridium 0.3 0.3 0.3 0.3 0.3 Selenium 0 0.04 0 0.04 0.04
Copper 0 0 0.05 0.05 0.25 Chloride 0.9 0.9 0.9 0.9 0.9 Alumina
98.50 98.46 98.45 98.41 98.21
______________________________________
The catalysts were each then contacted at reforming conditions in
separate runs with n-heptane with the results given in Table
II.
TABLE II ______________________________________ Yield, Wt. %
Catalyst C.sub.5 - Benzene Toluene
______________________________________ A 19.8 7.0 38.5 B 12.2 3.9
41.0 C 13.8 4.4 42.2 D 10.5 2.6 46.0 E 10.9 1.2 38.6
______________________________________
From these data it is shown that Catalyst D, the catalyst of this
invention, provides lower gas make with concurrent higher activity
and selectivity to aromatics than produced by any of Catalysts A,
B, C, or E. Catalyst E, a catalyst which also contains all of Pt,
Ir, Se and Cu, is woefully inadequate even as contrasted with
Catalysts A, B and C. The high copper content thus drastically
reduces the activity and selectivity of the catalyst, this catalyst
producing far less total aromatics than any of Catalysts A through
D.
It is apparent that various modifications and changes can be made
without departing from the spirit and scope of the present
invention, the outstanding features of which are that
hydrogenolysis can be suppressed and the yield and activity
maintenance can be improved even at high severity conditions.
* * * * *